1. Model Making

Introduce the parts of respiratory system by making a model using straws of different sizes and Q-tips. Large size straws using straw from bubble tea, regular straw and a narrow straw, such as those for hot coffee (but don’t forget to cut it through the middle).

Bubble tea straw

Regular straw

Straw for hot coffee

Model of respiratory system using straws

Start with the bubble tea straw to represent trachea, then regular straws to represent bronchi, coffee straws as bronchiols and finally the cotton end of Q-tips as alveoli (similar to the sac-like shape of alveoli). What you’ve done is a model to represent the passageway of air as you breath in and out.

Use of analogy
You can also compare this to the road system, for example…
Trachea ≈Expressway
Bronchi ≈ Exit of expressway (unlike expressway with multiple exits, there are only 2 bronchi in our body)
Bronchiole ≈Regular roads (branches off to streets and avenues, similar to branching observed in bronchiole)
Alveoli ≈ Carpark (loading and unloading taking place in carpark is similar to gaseous exchange taking place in alveoli)

2. Model of lungs

What’s the science behind it?When you pull down the knotted balloon, it increases the volume in the bottle, which lowers the pressure. As the environment has high pressure than the model, air rush in (because air moves from high to low pressure), hence inflating the balloon in the bottle. As the knotted balloon is released, volume in the bottle decreases, hence pressure increases. Hence, air moves out from the balloon and it deflates.

The knotted balloon in the model represents the diaphragm. Diaphragm is dome-shaped muscles located below the lungs. Its rhythmic contraction and relaxation results in breathing. Pulling down the knotted balloon is similar to diaphragm contracting. When the diaphragm contracts, it moves downwards, increasing volume of chest cavity.

4. Chest measurement

Grab a measuring tape to do a simple activity with your child. Lets compare the measurement of chest during inhalation and exhalation. Your child can compare the measurement and you can use this results to link to concepts of breathing. Also, let your child to do it on friends and family members too to inculcate scientific skills such measurement and communicating data.. You can use template here to record the results.

Extension (for 10 years old above)
Make it into project for your child as he/she do the measurement on friends and family members. Extend it for your child to make it into a report or poster to incorporate science skills and elements of STEAM.

5. Measuring breathing rate

To determine breathing rate, count for each time you breathe in for 1 minute.

Through this activity, you can introduce the concept that breathing rate increases during strenuous activity.

Science behind it
During physical activity, such as running, the muscle cells need more energy. Breathing rate increases to transport oxygen at a faster rate to cells to increase the rate of respiration, hence release more energy.

Here’s another Kitchen Science experiment – ice cream in a bag. You can easily get ingredients needed for this activity and with easy steps that kids can do it without making a mess (just make sure the ziplock bags are tightly sealed! and double ziplocked if you’re really worried). It’s also quick so kids won’t get impatient with it. The best part? It’s yummy and you can create your own flavour!

Steps:
1. Add heavy cream, milk , sugar and vanilla in a container. Stir well.
2. Transfer the content into a zipper-lock bag.
3. Seal the zipper-lock bag tightly.
4. Place it into the other zipper-lock bag. Seal it tightly.
5. Add crushed ice into the large plastic container until it’s half filled.
6. Add 6 tablespoons rock salt.
7. Place the zipper-lock bag in the container. Seal it.
8. Shake and roll it for 10-15 minutes.

Science notes
Possible science topics that you can explore with your child through this activity are state of matter and changes in state. Below are possible questions you can discuss with your child.

Is ice-cream a solid or liquid? Is it simply frozen ice-cream is solid and melted ice-cream a liquid? Frozen ice-cream is actually a mixture of different states of matter! This website by American Chemical Society explains the state of matter of ice cream for young children.

What is the change of state observed? Quite a few changes of state take place in this activity! Th obvious ones are change of state from liquid to solid (milk to ice crystals) in the first bag and change of state from solid to liquid in the plastic container. Probe your child to observe the water droplets in the second bag after the shaking and rolling as most might missed this. The bag is empty, so how do water vapour appear in the bag? This is another change of state, from gas to liquid.

Why is salt added to the ice? The dairy mixture need to be colder than ice to freeze. The salt added to ice lowers the melting point of ice. This makes the ice colder than it was before, to even below 0 degrees Celsius, hence increases the freezing rate of the diary mixture.

Extension

Another possible extension to explore this property of salt is to compare the freezing rate or melting of ice in normal water and in salt water.

Lastly, some videos to support your child’s learning in the topics mentioned above.